Adhesive products such as labels, stickers, tapes, and similar articles, are normally comprised of a surface sheet or facestock, a layer of adhesive, normally pressure-sensitive, secured to the back face of such surface sheet, and a removable paper backing sheet or release liner secured to the adhesive layer by a low surface-energy bond, such as a silicon coating, for ultimate removal when the label, sticker, or the like, is to be affixed to an article or substrate for end-use purposes. The backing sheet can be difficult to remove because no edge is usually exposed to facilitate grasping the backing sheet for its removal.
One approach to overcoming the difficulties encountered in removing backing sheets, is to crush-score the backing sheet before it is secured to the layer of adhesive and before it is silicone-release-coated. Crush-scoring leaves a line in the backing sheet that has been weakened by a compaction of the fibres in the sheet. When a label, sticker or the like is to be affixed, it can be flexed to cause the backing sheet to split or tear along the score line, creating a pair of exposed edges for grasping the backing sheet. The final dimensions of the labels, stickers or the like to be produced, often makes it advantageous to arrange the score lines in a diagonal pattern on the backing sheet, to maximize the length of score line available on the back of the product for creating exposed edges.
The amount of weakening that takes place during crush-scoring, however, must be carefully controlled to prevent splitting or tearing of the backing sheet while it is being processed or prepared for use, and to avoid producing labels, stickers or the like where splitting or tearing prematurely occurs or does not occur upon flexing.
Forming diagonal scores across a web of paper for release-liner use has been determined, with proper spacing of scores, to enable labels of any size to be cut from the web, with high statistical assurance that it will contain at least one edge-to-edge score to insure a crack-and-peel feature, i.e., the ability to form a crack at any score line and peel the backing across any other score line present.
The present invention is directed to a system for uniform diagonal crush-scoring at a constant and controllable pressure, to achieve a product of the highest quality.